1. Field of the Invention
The present invention relates to a headlight device having a high voltage electric-discharge lamp for use in an automobile.
2. Description of Related Art
Recently, a high voltage electric-discharge lamp is coming in use as a light source for an automobile headlight device. The high voltage electric-discharge lamp (hereinafter referred to as a discharge lamp) emits light from a light source generated by arc-discharge powered by a square alternating voltage or a direct current voltage. In case the discharge lamp is powered by an alternating voltage, electromagnetic noises are generated every time polarities of the voltage alternate. In case the discharge lamp is driven by a direct current voltage, the noises are generated at a time when the discharge lamp is turned on. Because the electromagnetic noises have a frequency band of several-tens MHz, they are harmful not only to a radio receiver and a television set mounted on a vehicle equipped with the discharge lamp but also to those mounted on other vehicles driving ahead of the vehicle.